Limbs have very complex shapes. They are not cylindrical or regularly shaped in any sense. Therefore, fitting a limb with a compression garment that is made from a single piece of material presents special design problems that must be addressed to fit complex limb curvatures with what is basically a single piece of planar material. If limbs were cylindrical, then bending a planar shape around a cylindrical limb would present no particular problem because a plane will readily bend around a cylinder and even a conical volume. However, limbs have complex shapes with varying complex curvatures. These shapes may hereinafter be referred to as limb hulls. The problem of fitting a planar piece of material around a limb hull may be analogous to wrapping a sheet of paper around an apple. Even though an apple has a much simpler curvature shape than a limb, one can immediately see that a planar sheet of paper would have to be altered significantly in order to fit neatly around the apple.
The challenge of fitting a limb neatly with a planar sheet is only one part of the design problem. A therapeutic compression garment must also be designed so that proper compression levels and compression gradients are provided for each area of an affected limb. Another important aspect related to compression is to design the compression garment such that the proper compression levels and compression gradients are directed at the limb in a desired direction (hereinafter, a compression magnitude with a compression direction is called a compression vector). Therefore, the single piece compression garment must have the properties of good fit and proper therapeutic compression levels and compression vectors.
A further challenge related to the design of a single piece compression garment is patient comfort. A planar piece of material may be cut to provide a good fit and proper compression, but if it results in patient discomfort due to pinching, buckling, or other reasons, the patient is unlikely to be compliant in wearing the compression garment and may not benefit from the therapy.
Another aspect of an effective single piece compression garment is that it should have good structural integrity. For example, if a compression garment made from a single piece of material has many lengthy cuts so that a good fit may be achieved, it may have little structural integrity and may be unwieldy to use. For a single piece compression garment to have high structural integrity, it is important to design it such that each cut is carefully planned so as to minimize the number of cuts, thereby making a compression garment that feels whole and is easy to use.
The use of properly fitting compression garments is important in treating various conditions. For example, excessive interstitial fluid accumulation, referred to as edema, may arise from a variety of illnesses and conditions, including venous valvular insufficiency, postphlebotic syndrome, posttraumatic swelling, postoperative swelling, congestive heart failure related swelling, hypoalbuminemia related swelling, drug related swelling, and lymphedema. Compression apparatus method and systems control edema by reduction of interstitial fluids which increases nutrient delivery to tissues, removes waste from tissues, relieves pain from swelling, and decreases risk of infection. However, prior-art compression technologies have certain drawbacks as explained below.
Wounds complicate the problem because traditional compression apparatus may restrict drainage of fluid from sores, cause skin breaks and/or ulcerations, and may promote wound breakdown and increased risk of blood clot formation in the veins.
Clinically, certain patient populations develop pressure necrosis to underlying skin and tissue breakdown occasionally occurs with traditional modalities, including compression stockings. This occurs most commonly over the anterior ankle where the tibialis tendon can be very prominent in some individuals. Some patients have a tibia which is prominent and plough-shaped, such that these patients can experience breakdown across parts of the shin area under these garments. Similarly, the malleoli and metatarsal heads of the 1st and 5th digits are occasional problems as well.
Some patients have troublesome anatomical morphologies, such as large bunions, metatarsal head protrusions, or accentuated ankle malleoli, which are predisposed to higher peak compression levels. Some patients requiring compression have fragile skin that cannot tolerate even moderately elevated compressive or shear forces. Patients with lymphedema and venous insufficiency often develop fibrotic areas within the tissues or may be lacking in lymphatic integrity.
Many of the above mentioned patients are prone to bacterial and fungal skin infections, all of which can be life threatening.
Particularly problematic in venous and lymphedema patients and other patients requiring long term compression is the incidence of dermatitis, causing itching, and discomfort which contribute to lack of compliance with compression and is therefore also detrimental to attempts at edema reduction and healing of wounds in edematous limbs.
Because of considerable variation in limb shapes and sizes, custom garments may traditionally be required. However, conventional custom garments take time to manufacture. It is not uncommon, for instance, for conventional custom compression stockings to take one month from date of order until the patient receives the garment. Furthermore, errors in manufacturing and measurement sometimes necessitate remanufacturing the garment or altering the garment in order to get a proper fit. This is very inconvenient for the patient, who needs therapeutic compression immediately, and must make-do with an off-the-shelf garment or bandage until the custom garment arrives and fits correctly.